Synthetic lubricant



Reiuued Aug. 9, 1949 SYNTHETIC LUBRICANT Orland M. Bell, Woodbnry,Howard D. Hartough, Pltman, and Harry J. Andreas, Jr., Woodbnry, N. 1.,assignors to Smelly-Vacuum Oil Company, Incorporated, a corporation ofNew York No Drawing. Original No. 2,443,083, dated June 8, 1948, SerialNo. 540,145, June 13, 1944. Application for reissue January 8, 1949,Serial No.

1-! illaims.

This invention has to do with the art 01 lubrication and, moreparticularly, has to do with the preparation of synthetic lubricants.

In the lubricant art, considerable progress has been realized in recentyears in the production of lubricants characterized by one or morespecific properties and adapted for particular uses. In the main, thisprogress can be attributed to two developments: the first, new refiningprocedures and, the second, addition agents capable of 1mpartingparticular properties to available lubricants. Although these lubricantsare somewhat superior to those formerly available in the art, ingeneral, they too suiTer in one or more respects. For example, whilesuch oils may have superior viscosity characteristics, etc., they mayhave undesirable oxidation characteristics, etc. Recently, however, inan effort to obtain superior lubricants endowed with specific andsuperior characteristics, a new field has been explored, namely, thesynthesis of lubricants from various materials. The products so obtainedhave been aptly described in the art as "synthetic lubricants."

While many of the synthetic lubricants recentl prepared have been foundto be desirable for various uses in view of a superior characteristicsuch as improved oiliness, viscosity, resistance to oxidation, etc.,they invariably have extremely high pour points which naturally militateagainst their wide use in the art. Generally, they suffer too from thedisadvantage of a failure to respond to pour point depressants when thelatter are incorporated therewith in relatively small amounts.

The present invention is predicated upon the discovery of a new andnovel class of synthetic lubricants-paraflin wax xylenes--which arecharacterized by relatively low pour points and which are responsive tosubstantial pour point depression upon the addition thereto of smallamounts of a novel class of pour point depressants, the esters ofalkyl-substituted phenols. The synthetic lubricants of this invention,in combination with the said pour point depressants, are allcharacterized by pour points of F. (A. S. T. M.) and are furthercharacterized by outstanding viscosity index values and resistance tooxidation.

Also contemplated herein is a method for the preparation of the said newand novel. synthetic lubricants, the method involving reactingcertainpartially halogenated paraflin waxes with xylene in the presenceof a Friedel-Crafts catalyst at a condensation temperature andthereafter septer.

arating the catalyst and any unchanged reactants from the reactionmixture so obtained. While the present method may be briefly summarizedby the foregoing statement, it is much more complex than as so stated,inasmuch as several of the factors recited therein are critical innature and must be followed religiously lest products of a somewhatinferior character be formed. Specifically, the several criticalfactors, all of which are interrelated, include the following:

1. Type or paraflin wax,

2. Degree of halogenation or the paraflln wax and 3. Proportions ofhalogenated paraflin wax and of axylene.

. or importance in the present method is the type of paraiiln wax used.We have found that when a crystalline paramn wax having a melting pointnot greater than about 140 F. is used, synthetic lubricants ofrelatively low pour point and susceptible to pour point depression areobtained. Particularly preferred waxes of this type,

however, are those having melting points from about F. to about F. Thesewaxes have a crystalline structure, as opposed to other parailin waxeswhich do not have a well-defined crystal structure and are amorphous in,charac- The latter are commonly referred to as amorphous waxes, and areconsidered to be undesirable for the purposes of this invention,

for such waxes would result in products having' relatively high meltingpoints and having comparatively little susceptibility to pour pointdepression. 0f the waxes used herein, we have found that particularlyoutstanding results are obtained with a crystalline paramn waxcontaining on the average of 24 carbon atoms and having a melting pointof about 126 F. It is to be understood, however, that all crystallineparaflin waxes characterized by melting points not greater than about F.and obtained from all sources, such as-petroleum wax fractions, theFischer- Tropsch synthesis, etc., are contemplated herein.

Accordingly, when used hereinafter, the expression wax unless otherwisequalified denotes the desired reactants: crystalline paraflin wax.

With regard to the degree of halogenation of wax which must be followed,it may first be said that all halogens may be used. In view of therelative cost, availability, etc., however, chlorine is preferred and,for this reason, the following description will be confined to thechlorinated waxes. It is essential that the chlorinated waxes reactedwith a xylene contain from 3 about 21 per cent to about 24 per centchlorine. When chlorine concentrations in excess of the maxima, about 24per cent, are used, the products obtained therefrom are characterized byrelativel high viscosities and do not have sufficiently low pour points-F.when small amounts of the aforesaid pour point depressants areincorporated therewith. Similarly, when chlorine concentrations lowerthan about 21 per cent are used, the products so obtained containexcessive amounts of wax and have undesirably high pour points, about 0F.

It should be understood that a 21 per cent chlorinated wax is oneprepared by introducing chlorine into a crystalline paraffin wax, asdefined above, until the weight of the wax has increased about 21 percent. Such a product is predominantly comprised of dichlorinated waxwith substantial quantities of unchlorinated wax,

mono-chlorowax and more highly chlorinated wax. It should also beunderstood that when other halogens are used in placeof chlorine in thewax reactant. the foregoing percentage range from about 21 per cent toabout 24 per cent, will be subject to change in proportion to therelative atomic weights of the individual halogens.

Of primary importance are the relative amounts or proportions of thereactants, namely, chlorinated wax and a xylene. In order to obtain thedesired product, at least onemole ofa xylene is reacted with an amountof chlorinated wax which containsone atomic weight of chlorine. Inshort, at least one mole of, a xylene is used for each atomic weight ofchlorine in the chlorinated wax reactant. Accordingly, it will be clearthat the reaction products obtained with such proportions arepredominantly monowax xylenes. If less than one mole of a xyleneis usedfor each atomic weight of chlorine in a chlorowax, products of lessdesirable character are obtained. The latter products, unlike thosecontemplated herein, suffer from their failure to give pour points of 0F. or lower when small amounts of the aforesaid pour point depressantsare used therewith.

The reaction temperatures useful in the present method are thosenormally referred to in the art as Friedel-Crafts condensationtemperatures. While temperatures from about 25 C. to about 145 C. may beused satisfactorily, the preferred reaction temperatures are about135445 0., the boiling points of xylenes.

The amount of catalyst used in the condensation should be relativelysmall, that is, a catalytic amount. Generally, amounts from about 1 percent to about per cent by weight of the chlorowax reactant aresatisfactory, and amounts of the order of 3 per cent are preferred.Catalysts such as aluminum chloride, zinc chloride, ferric chloride,boron trifiuoride. hydrogen fluoride, etc., serve the purpose of thisinvention; and for this reason, the catalysts are definedbroadly hereinas those capable of effecting a Friedel-Crafts-type condensation.Particularly preferred, however, is aluminum chloride.

In order to more fully illustrate the method by which our syntheticlubricants are obtained, the following typical procedure is detailedhereinbelow.

EXAMPLE Preparation of wax-xylene (1 -21) melting point) are placed in aflask equipped with a thermometer, reflux condenser and an electricallydriven stirrer. The chlorowax used contains 1 atomic weight of chlorine.Aluminum chloride (5 grams) is slowly added to the chlorowax and xyleneat a temperature of about 25 C. while agitating the same. Thetemperature is then raised to the reflux temperature of the xylene-about140 C.and maintained for about 1 hour to complete the condensation ofchlorowax and xylene. The reaction mixture is then purified by filteringthrough a contact clay to remove aluminum chloride. The filtrate is thenheated to remove excess xylene and the residue obtained thereby is awax-substituted xylene containing some unreacted wax, about 5 to percent unreacted wax. The unreacted wax is removed by vacuum distillation(it may also be removed by conventional dewaxing procedures).

The product is wax-xylene (1-21).

Parenthetical expressions (1-21) indicating that xylene is substitutedwith 1 wax group and that the chlorowax used in the preparation thereofcontained 21 per cent chlorine are used hereinafter to so identify eachproduct illustrative of the present invention, as well as relatedproducts which do not possess the superior characteristics of thelubricants prepared as outlined above.

It will be understood, or course, that any unreacted xylene can be usedagain in the preparation of additional product, and that unreacted waxcan be further chlorinated for future use.

Although we have illustrated our synthetic lubricants by a product freeof unreacted wax (removed by vacuum, distillation, solvent dewaxing,etc), it is to be understood thatit is not essential that all of theunreacted wax be removed. Accordingly, both wax-free syntheticlubricants and synthetic lubricants containing relatively small amountsof unreacted wax are contemplated herein.

In order to'illustrate the superior characteristics of the syntheticlubricants of the present invention,.several typical examples arepresented hereinbelow in Table I. There, the S. U. V. at

' 210 F., viscosity index and A. S. T. M. pour test of the abovesynthetic lubricants are shown; all of these characteristics and methodsfor determining the same are well known and need not be furtherdescribed at this point. In addition, the response of thesesyntheticlubricants with and without a pour point depressant is alsodemonstrated. Also present in Table I for comparison with the syntheticlubricants contemplated herein are several typical products which aremuch less desirable for use as lubricants for one reason or another. Forconvenience in identifying the latter products, they are preceded by an"X" in Table I.

Table I s. U. v. A.S.T. M. Produet V. I Pour Test, F OF F.) with Xwax-xylene (l12) 44. 4 119.0 +25 15 fax-xylene (1-21) 63. 6 89. 5 5Wax-xylene (124) 75. 4 a 75. 5 +20 5 X wax-xylcne (l-27) i241) 49. 7 r Xwax-xylene (128). 127. 2 47. 3 +20 +15 1 A=p0ur depressant: tetra-waxphenol phtlialate.

It will be clear on inspection of the pour test results set forth inTable I that wax-xylenes prepared from a chlorowax containing 12, 27 and28 per cent chlorine do not give pour points of 0 1 and lower when asmall amount of pour depressant A is incorporated therein. Surprisingly,however, when the chlorowax reactant contains from about 21 per cent toabout 24 per cent chlorine, the wax-xylenes obtained therefrom aresusceptible or a pour point lowering to at least F. when small amountsof pour depressant A are added thereto.

It will be further noted from inspection oi the results provided inTable I that the wax-xylenes (1-21) to (1-24) have viscosities (S. U. V.

' 210 F.) and viscosity indexes which make Table II A S T M A. S T. M.

Product z do fi V. I Pour Test, 3 35 Wax-xylene 51-21)--.. 63.6 89. 6+20 Wax-xylene l24)- 75.4 75.5 +20 5 X wax-xylene (ii-21).. 53. 7 110.9+20 +20 X wax-xylene (ii-24).. 55. 8 110. 1 +20 +20 A-pour depressant:tetra-wax phenol phthalate.

It will be seen that wax-xylencs (l-21) and (1-24) in Table II have pourpoints of less than 0" F. with pour pointdepressant A. Yet, waxxyienesprepared with chlorowaxes containing the same percentages (21 and 24) ofchlorine as those used in the prepaartion of the aforesaid monowaxsynthetic lubricants, but prepared with more than one mole of a xylenefor each atomic weight of chlorine in the chlorowax are not so favorablycharacterized.

In Tables I and II above, tetra-wax phenol phthalate--which ispreferred-is used to illustrate the class of pour point depressantscontemplated herein. It is to be understood, however, that all esters ofalkyl-substituted phenols, particularly those in which the alkylsubstituent is paraflln wax, are broadly contemplated. Such depressantsare described in detail in Patent Nos. 2,048,465 and 2,048,466, issuedto 0. M. Reifl et al. Although varying amounts of these materials may beused herein, satisfactor results are obtained with concentrations offrom about 0.125 per cent to about 1.0 per cent.

We claim:

1. A lubricant of low pour point comprising a synthetic lubricant havingincorporated therewith a small amount, sufficient to characterize thesaid lubricant with a pour point at least as low as 0 F., of an ester ofan alkyl-substituted phenol, said. synthetic lubricant being preparedfrom a crystalline paraffin wax having a melting point not greater thanabout 140 F. and a xylene by: partially halogenating the crystallineparaflin wax to form a mixture of halogenated wax and substantiallyunhalogenated wax containing an amount of halogen corresponding to fromabout 21 per cent to about 24 per cent chlorine; mixing the halogenatedwax and unhalogenated wax with said xylene in the proportion of at leastone mole of xylene to each atom of halogen in the halogenated waxmixture; adding thereto a catalyst capable of effecting a Friedel-Craitstype condensation; heating the mixture thus obtained at a lriedel-Crafts condensation temperature until substantially all of thehalogenated wax has reacted with said xylene; and separating theFriedel-Crai'ts catalyst. unreacted xylene and unhalogenated wax fromthe reaction mixture so obtained, to obtain said synthetic lubricant.

2. A lubricant of low pour point comprisinga synthetic lubricant havingincorporated therewith a small amount, sufllcientto characterize thesaid lubricant with a pour point at least as low as 0 F., of an ester oran alkyl-substituted phenol, said synthetic lubricant being preparedirom a crystalline paraflin wax having a melting point not greater thanabout 140 Rand a xylene by: partially ehlorin'ating the crystallineparaffln wax to form a mixture of chlorinated wax and unchlorinated waxcontaining from about 21 per cent to about 24 per cent chlorine; mixingthe chlorinated wax and unchlorinated wax with said xylene in theproportion of at least one mole of xylene to each atom of chlorine inthe chlorinated wax mixture; adding a Friedel-Crafts catalyst thereto;heating the mixture thus obtained under refluxing conditions to therefluxing temperature of said xylene until substantially all of thechlorinated wax has reacted with said xylene; and separating theFriedel-Craits catalyst, unreacted xylene and unchlorinated wax from thereaction mixture so obtained, to obtain said synthetic lubricant.

3. A lubricant of low pour point comprising a synthetic lubricant havingincorporated therewith a small amount, sufllcient to characterize thesaid lubricant with a pour point at least as low as 0 F., of an ester ofan alkyl-substituted phenol, said synthetic lubricant being preparedfrom a crystalline parafiin wax having a melting point between about F.and about F.,

and a xylene by: partially chlorinating the crys- 'talline paraflin waxto form a mixture ofv chlorinated wax and unchlorinated wax coning themixture thus obtained under refluxing conditions to the refluxingtemperature of said xylene until substantially all of the chlorinatedwax has reacted with said xylene; and separating the Friedel-Craftscatalyst, unreacted xylene and unchlorinated wax from the reactionmixture so obtained, to obtain said synthetic lubricant.

4. A lubricant of low pour point comprising a synthetic lubricant havinincorporated therewith a small amount, sufiicient to characterize thesaid lubricant with a pour point at least as low as 0 F., of an ester ofan alkyl-substituted phenol, said synthetic lubricant being preparedfrom a crystalline paraflin wax having an average of about 24 carbonatoms and a melting point of about 126 F., and a xylene by: partiallychlorinating the crystalline paraflin wax to form a mixture ofchlorinated wax and unchlorinated wax containing from about 21 per centto about 24 per cent chlorine; mixing the chlorinated wax andunchlorinated wax with said xylene in the proportion of at least onemole of xylene to each atom of chlorine in the chlorinated wax mixture;adding a Friedel-Crafts catalyst thereto; heating the mixture thusobtained under refluxing conditions to the refluxing temperature of saidxylene untiisubstantially' all of the chlorinated wax has reacted withsaid xylene; and separatin the Friedel-Crafts catalyst, unreacted xyleneand unchlorinated wax from the reaction mixture so obtained to obtainsaid synthetic lubricant.

5. A lubricant of low pour point comprising a synthetic lubricant havingincorporated therewith a small amount. sufllcient to characterize thesaid lubricant with a pour point at least as low as F., of an ester ofan alkyl-substituted phenol, said synthetic lubricant being preparedfrom a crystalline paramn wax having a melting point not greater thanabout 140 F. and a xylene by:

partially chlorinating the crystalline paraflin wax to form a mixture ofchlorinated wax and um chlorinated wax containing from about 21 per centto about 24 per cent chlorine; mixing the chlorinated wax andunchlorinated wax with said xylene in the proportion of at least onemole ofxylene to each atom of chlorine in the chlorinated wax mixture;adding a catalytic amount of aluminum chloride thereto; heating themixture thus obtained under refluxing conditions to the refluxingtemperature of said xylene until substantially all of the chlorinatedwax has reacted with said xylene; and separating the aluminum chloride.unreacted xylene and unchlorinated wax from the reaction mixture soobtained, to obtain said synthetic lubricant.

6. A lubricant of low pour point comprising a synthetic lubricant havingincorporated therewith a small amount, sufiicient to characterize thesaid lubricant with a'pour point at least as low as 0 F., of an ester ofan alkyd-substituted phenol, said synthetic lubricant being preparedfrom a crystalline paraflin wax having a melting point not greater thanabout 140 F. and a xylene by: partially chlorinating the crystallineparaflln wax to form a mixture of chlorinated wax and unchlorinated waxcontaining from about 21 per cent to about 24 per cent chlorine; mixingthe chlorinated wax and unchlorinated wax with said xylene in theproportion of at least one mole of xylene to each atom of chlorine inthe chlorinated wax mixture; adding a F'riedel-Crafts catalyst thereto;heating the mixture thus obtained at about 140 C. until substantiallyall of the chlorinated wax has reacted with said xylene; and separatingthe Friedel-Crafts catalyst, un-' reacted xylene and unchlorinated waxfrom the reaction mixture so obtained, to obtain said syntheticlubricant.

7. A lubricant of low pour point comprising a synthetic lubricant"having incorporated therewith a small amount, sufilcient to characterizethe said lubricant with a pour point at least as low as 0 F., of anester of a wax-substituted phenol, said synthetic lubricant beingprepared from a crystalline parailin wax having a melting point notgreater than about 140 F. and a xylene by: partially chlorinating thecrystalline paraflln wax to form a mixture of chlorinated wax andunchlorinated wax containing from about'21 per cent to reacted xyleneand unchlorinated wax from the reaction mixture so obtained, to obtainsaid synthetic lubricant.

8. A lubricant of low pour point comprising a synthetic lubricant havingincorporated therewith a small amount, sufllcient to characterize thesaid lubricant with a pour point at least as low as 0 of tetrawax phenolphthalate, said synthetic lubricant being prepared from a crystallineparaflln wax having a melting point not greater than about 140 F. and axylene by: parabout 24 per cent chlorine; mixing the chlorinated wax andunchlorinated wax with said xylene in the proportion of at least onemole of xylene to each atom of chlorine in the chlorinated wax mixture;adding a Friedel-Crafts catalyst thereto; heating the mixture thusobtained under-refluxing conditions to the refluxing temperature of saidxylene until substantially all of the chlorinated wax has reacted withsaid xylene; and separating the Friedel-Crafts catalyst, un-

tialiy chlorinating the crystalline paramn wax to form a mixture ofchlorinated wax and unchlorinated wax containing from about 21 per centto about 24 per cent chlorine; mixing the chlorinated wax andunchlorinated wax with said xylene in the proportion of at least onemole of xylene to each atom of chlorine in the chlorinated wax mixture;adding a Friedel-Crafts catalyst thereto; heating the mixture thusobtained under refluxing conditions to the refluxing temperature of saidxylene until substantially all of the chlorinated wax has reacted withsaid xylene: and separating the Friedel-Crafts catalyst, unreactedxylene and unchlorinated wax from the reaction mixture so obtained. toobtain said syn thetic lubricant.

9.. The method of preparing a lubricant having a pour point at least aslow as 0 F. which comprises: partially halogenating a crystallineparafiin wax having a melting point not greater than about F. to form amixture of halogenated wax and substantially unhalogenated waxcontaining an amount of halogen corresponding to from about 21 per centto about 24 per cent chlorine; mixing the halogenated wax andunhalogenated wax mixture with a xylene in the proportion of at leastone mole of xylene to each atom of halogen in the halogenated waxmixture; adding thereto a catalyst capable of eil'ecting aFriedel-Crafts type condensation; heating the mixture thus obtained at aFriedel-Crafts condensation temperature until substantially all of thehalogenated wax has reacted with said xylene; separating theFriedel-Crafts catalyst, unreacted xylene and unhalogenated wax from thereaction mixture so obtained; and adding thereto a small amountsuflicient to characterize the said lubricant with a pour point at leastas low as 0 F. of an ester of an alkyl-substituted phenol.-

10. The method of preparing a lubricant having a pour point at least aslow as 0 F. which comprises: partially chlorinating a crystallineparailln wax having a melting point not greater than about 140 F. toform a mixture-of chlorinated wax and substantially unchlorinated waxcontaining from about 21 per cent toabout 24 per cent chlorine; mixingthe chlorinated wax and unchlorinated wax mixture with a xylene in theproportion of at least one mole oi xylenato each atom of chlorine in thechlorinated wax mixture; adding thereto a Friedel-Crafts catalyst;heating the mixture thus obtained under refluxing conditions to therefluxing temperature of xylene until substantially all of thechlorinated wax has reacted with said xylene; separating theFriedel-Craits catalyst, unreacted xylene and unchlorinated wax from thereaction mixture so obtained; and adding thereto a. small amountparaflinic wax having a melting point not greater than about 140 F. toform a mixture of halogenated wax and substantially unhalogenated waxcontaining an amount of halogen corresponding to from about 21 per centto about 24 per cent chlorine; mixing the halogenated wax andunhalogenated wax mixture with a xylene in the proportion of at leastone mole of xylene to each atom 01' halogen in the halogenated waxmixture; adding thereto a catalyst capable of effecting a Friedel-Craftstype condensation; heating the mixture thus obtained at a Friedel-Craftscondensation temperature until substantially all of the halogenated waxhas reacted with said xylene; separating the Frledel-Crafts catalyst,unreacted xylene and unhalogenated wax from the reaction mixture soObtained; and addingthereto a small amount suflicient to characterin thesaid lubricant with a pour point at least as low as 0 F. of an ester ofan alkyl-substituted phenol. l

12. The method of preparing a lubricant having a pour point at least aslow as 0 F. which comprises: partially chiorinating a crystallineparailln wax having a melting point not greater than about 140 F. toform a mixture-of chlorinated wax and substantially unchlorinated waxcontaining from about 21 per cent to about 24 per cent chlorine; mixingthe chlorinated wax and unchlorinated wax mixture with a xylene in theproportion of at least one mole of xylene to each atom of chlorine inthe chlorinated wax mixture; adding thereto a Friedel-Crafts catalyst;heating the mixture thus obtained under refluxing conditions to therefluxing temperature I than about 140 F. to form a mixture ofhalogenated wax and substantially unhalogenated wax containing an amountof halogen corresponding to from about 21 per cent to about 24 per centchlorine; mixing the halogenated wax and unhalogenated wax mixture witha xylene in the proportion of at least one mole of xylene to each atomof halogen in the halogenated wax mixture; adding thereto a catalystcapable of effecting a Friedel-Crafts type condensation; heating themixture thus obtained at a Friedel-Crafts condensation temperature untilsubstantially all of the halogenated Wax has reacted with said xylene;separating the Friedel-Crafts catalyst, unreacted xylene andunhalogenated wax from the reaction mixture so obtained; and addingthereto a small amount suflicient to characterize the said lubricantwith a pour point at least as low as 0 F. of tetrawax phenol phthalate.

14. The method of preparing a lubricant having a pour point at least aslow as 0 F. which comprises: partially chlorinating a crystallineparaflln wax having a melting point not greater than about 140 F. toform a mixture of chlorinated wax and substantially unchlorinated waxcontaining from about 21 per cent to about 24 per cent chlorine; mixingthe chlorinated wax and unchlorinated Wax mixture with a xylene in theproportion of at least one mole of xylene to each atom of chlorine inthe chlorinated wax mixture; adding thereto a Friedel-Craits catalyst;heating the mixture thus obtained under refluxing conditions to therefluxing temperature of xylene until substantially all of thechlorinated wax has reacted with said xylene; separating theFriedel-Crafts catalyst, unreacted xylene and unchlorinated wax from thereaction mixture so obtained; and adding thereto a small amountsufiicient to characterize the said lubricant with a pour point at leastas low as 0 F. of tetrawax phenol phthalate.

ORLAND M. REIFF.

HOWARD D. HARTOUGH. HARRY J. ANDRESS, JR.

No references cited.

